I was at an early Tally Hall concert and I heard a song I really liked, but it isn’t on MMMM or Complete Demos. What happened to it?

The song you heard was probably either a cover song (Tally Hall has gone off on limbs such as “Blinded by the Light”, “You’re Just What I Needed”, “Praise You” and “Just A Friend”) or a public test of a preliminary version of a song. In fact, there are even lyric sheets to one such song which, confirmed by Andrew, was performed once prior to Tally Hall forming, and then never used again. Tally Hall reserves their albums for only the best songs.